This proposal will analyze how the primate retina represents motion information, and how this information compares with psychophysical performance in human observers and with published studies on the receptive field properties of cortical area MT. The experiments will involve multielectrode recordings from an in vitro preparation of macaque retina. Aim 1. The P.I. will look at how the accuracy of motion discrimination is represented in the retina, how this might be represented by neural ensembles, and how the M and P ganglion cells might differ in their individual accuracy. Aim 2. This goes farther into the question of the role of spike timing in generating psychophysical performance. Aim 3. Does retinal signaling limit accuracy of behavioral and cortical motion sensing? This part will include psychophysical studies as well as correlation with recordings in MT obtained from other investigators.